Chen Baoding, Zuo Yachao, Lv Yanrong, Zhang Hao, Yang Jiawen, Gu Yun, Yang Junxiong, Yuan Meijin, Yang Kai
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, No. 135, Xingang Xi Road, Guangzhou 510275, China.
Virus Evol. 2025 Jul 25;11(1):veaf055. doi: 10.1093/ve/veaf055. eCollection 2025.
As crucial regulators of insect populations in nature, baculoviruses are promising biopesticides. However, due to the scarcity of individuals with overt disease and the sporadic nature of the epidemic, our knowledge of baculovirus ecology is very limited, which impacts the effective utilization of these viruses in biocontrol. Cnaphalocrocis medinalis granulovirus (CnmeGV) specifically infects the rice leaffolder, which is the main pest of rice. In this study, we identified a population of CnmeGV that can cause a persistent epizootic in Dahuai town, Enping County, Guangdong Province, China. We sequenced the whole genomes of 138 CnmeGV isolates collected from Dahuai town for four years, reporting for the first time the genetic structure of a natural population of baculovirus. The results indicated that a long-term endemic population of CnmeGV displayed substantial genetic variation. The discriminant analysis of principal components revealed that the genetic structure of CnmeGV is clearly differentiated annually and seasonally (by the rice-growing season). CnmeGV epidemics typically occur in three waves (W1, W2, and W3) during each rice-growing season. Although the genetic structures of the CnmeGV isolates within the same rice-growing season were closely related, nucleotide diversity analysis revealed that the CnmeGV genomes exhibit higher heterozygosity levels in the initial epidemic wave compared to subsequent waves. We also found that host behaviour, virus distribution, plant structure, and weather are important factors in the recurrence of CnmeGV epizootics. Leveraging these ecological insights, we revealed the potential transmission route of CnmeGV, named 'From W1 in sheath to W2+ in fold', during continuous epidemics in natural environments. This study provides important insights into the ecology and evolution of host-pathogen interactions and the route helps develop more effective biocontrol strategies.
杆状病毒作为自然界中昆虫种群的关键调节因子，是很有前景的生物杀虫剂。然而，由于显性疾病个体稀少且疫情具有散发性，我们对杆状病毒生态学的了解非常有限，这影响了这些病毒在生物防治中的有效利用。稻纵卷叶螟颗粒体病毒（CnmeGV）专门感染稻纵卷叶螟，而稻纵卷叶螟是水稻的主要害虫。在本研究中，我们鉴定出一群能在中国广东省恩平市大槐镇引发持续性流行病的CnmeGV。我们对从大槐镇采集的138株CnmeGV分离株进行了为期四年的全基因组测序，首次报道了杆状病毒自然种群的遗传结构。结果表明，长期地方性流行的CnmeGV种群表现出显著的遗传变异。主成分判别分析显示，CnmeGV的遗传结构在年度和季节上（按水稻生长季节）有明显差异。CnmeGV疫情通常在每个水稻生长季节出现三波（W1、W2和W3）。尽管同一水稻生长季节内CnmeGV分离株的遗传结构密切相关，但核苷酸多样性分析表明，与后续波次相比，CnmeGV基因组在初始流行波中的杂合度水平更高。我们还发现宿主行为、病毒分布、植物结构和天气是CnmeGV流行病复发的重要因素。利用这些生态学见解，我们揭示了在自然环境连续流行期间CnmeGV的潜在传播途径，即“从叶鞘中的W1到卷叶中的W2+”。本研究为宿主-病原体相互作用的生态学和进化提供了重要见解，该途径有助于制定更有效的生物防治策略。
